There are some private lenders out there who are willing to do this, but there is a good chance it will not be in your best interest.
On your federal loan (is it a Stafford loan?) there is a grace period available as many deferment & forbearance options available if you ever need help or lose your job, etc. On private loans there is typically very little or no time available for deferment or forbearance. In addition, private loan interest rates are higher. The reason for this is because federal loans are backed by the government, there for there is no chance the lender is going to lose money if you don't pay. With private loans this obviously is not the case, so they jack up the interest rates to make up for it.
So not only will it probably raise your interest rate, you will lose your options for assistance, but you will also probably come out paying more interest in the long run. Typically consolidation will stretch your payment out over a longer period of time, so instead of paying interest for 10 years (the typical length of repayment on a federal Stafford loan) you may be paying for 20-25+ years. That means 10-15 extra years worth of interest.
I hope this helps at least a little bit. If you have any questions feel free to email me!
Work for student loan company.